EP1224476B1 - Test probe for a device for testing printed circuit boards - Google Patents

Abstract

A probe for a circuit board tester as well as to an adapter and a circuit board tester. The probe comprises a needle and a sleeve, the needle being shiflingly guided in the sleeve and the needle protruding at least 10 mm from the sleeve, more particularly more than 20 mm. In one embodiment, the needle is conically tapered to a contact tip at least in a portion protruding from the sleeve. With the probe in accordance with the invention, adapters for circuit boards can be produced comprising contacts in high-density, the probes simultaneously acting resiliently.

Description

The present invention relates to a test pin for a device for testing Printed circuit boards as well as an adapter and a device for testing printed circuit boards.

Various designs of test pins or test needles are state of the art known for use in device for testing printed circuit boards. A device according to the prior art is shown in Fig. 6. With a grid adjustment adapter R becomes a predetermined, regular basic grid of a basic grid field G to the usually irregular arrangement of the circuit board test points T one PCB P to be tested implemented. The grid adjustment adapter R points in the Usually several spaced-apart guide layers F, in which guide holes are inserted to hold the test needles N. The test needles are N in the adapter R rigidly and obliquely arranged so that they are contact points of the regular Can electrically connect the basic grid to the circuit board test points T, since these differ from the regular arrangement of the basic grid.

To compensate for unevenness in the circuit board test points of the test items PCB and for an electrically safe contact with the basic grid G the raster adjustment adapter R is connected to a full raster cassette V, which are equipped with resilient test pins S in the respective grid of the basic grid is. The full grid cassette is fully populated with pins, while the grid adjustment adapter usually only has as many needles N as that testing circuit board has circuit board test points T. The design of the needles N are usually rod-shaped and usually have shoulders or thickened ends, such as in EP 0 149 776 B2 and DE G 90 14 236.5 U1.

Modern circuit boards have or are numerous internal wiring levels intended for the direct reception of highly integrated ICs. In particular through the use of high-density arrangements of pads, such as Ball Grid Arrays (BGA), are the requirements for the number of to be contacted and contact points to be measured on a printed circuit board increased significantly. at the same time is the inter-contact distance for such printed circuit boards up to approx. 0.25 mm (10 with) dropped. For such adapters in this field of application, one therefore uses extremely thin needles, for example, only a diameter of 0.1 mm or 0.2 mm. However, these needles are extremely unstable, so that many guide positions must be provided in the adapter in order to be able to guide them safely. The effort to manufacture a test fixture to be tested for each type PCBs must be made individually, is due to the requirements mentioned very high.

In the article: "SMD technology changes test equipment" from Feinwerktechnik & Messtechnik 98, No. 7/8, pages 317-318, a contact pin for SMD-equipped printed circuit boards is disclosed, which has a pin sleeve and a piston which is displaceable in the pin sleeve has. The diameter of the piston is 1.3 mm. Herein, pens with less Wall thickness of the pin sleeve and with a small shaft diameter of the piston described as disadvantageous.

US 4,4,896,107 shows contact pins with tapered tips. These contact pins have a maximum thickness of 1.3-1.4 mm in the area of the shaft, wherein the head formed on the contact pin has a diameter of 2 mm.

DE 36 43 305 A1 shows a spring contact pin with an elongated metallic Cylinder, which serves as a sleeve and a one-piece metal tube-screw-spring part has, which is inserted in the sleeve and one in the sleeve movable contact pin forms.

Another contact pin emerges from DE 34 26 295 A1. This contact pin again has a sleeve and a piston. The piston is flattened provided, in which a pinch groove of the sleeve engages. The provision of such Contour shows that the piston used here is much thicker than the one according to the invention Needle is.

US 4,633,176 relates to an adapter for testing printed circuit boards in the side deflectable test pins are provided, which by means of a conical tip and with the conical tip interacting bores deflected and to predetermined Contact points of the circuit board to be tested are aligned.

The invention has for its object to provide a test pin that meets the requirements in ever increasing numbers, arranged closely together Connection areas when measuring or contacting modern circuit boards becomes. There is also the task of an adapter and an improved device to create for testing printed circuit boards.

The invention has a test pin with the features to solve these problems of claim 1 and an adapter with the features of claim 11 and a Device for testing printed circuit boards with the features of claim 14. Advantageous refinements of this are the subject of the respective subclaims.

A test pin according to the invention for a device for testing printed circuit boards is characterized in that it comprises a needle and a sleeve, the needle is slidably guided in the sleeve and the needle at least 10 mm from the Protrudes sleeve, especially more than 20 mm. The needle tapers off on that the sleeve protruding area conical up to a contact tip.

This protruding, conically tapering area of the contact pin allows one very dense positioning of the contact pins in the area of their contact tips, since the Contact pin in this area is very low due to the tapered tip Has thickness.

By guiding the needle in the sleeve, there is an improved inherent rigidity at the same time created resilient balancing ability of the test pin. Further points a test pin according to the invention has good integration capability in adapters for scanning very dense contact surface arrangements with small distances between the Contact areas.

This combination of a needle tapering to the contact tip and a sleeve, from which the needle protrudes a considerable distance allows a tight one Placing several test pins in the area of their contact tips indicates the necessary Stiffness and is simple.

Furthermore, an adapter according to the invention consists of at least two parallel layers, in which resilient test pins of the type mentioned above in continuous Recesses are stored, the test pins are partially arranged obliquely and contact tips of the test pins for contacting a test object protrude as well the test pins on a side of the adapter opposite the device under test Contacting of a basic grid provided with contacts are. This is divided into two by an adapter according to the invention Full grid cassette with resilient pins and a rigid needle adapter for adjustment from a regular grid of common basic grids to any The grid of a test object has been removed. Here the sleeve takes over essential support and Management tasks so that the number of inner layers can be kept low. In adapters, the hole pattern of each layer must be calculated individually by computer and can be created using high-precision CNC machines with a drilled hole pattern, so that each saving of a location entails a considerable cost reduction brings. Overall, the present invention makes it single and very compact Adapter with a significant reduction in the number of individual parts and correspondingly cheaper Costs created.

A device according to the invention for testing printed circuit boards is also distinguished through a structure with a regular basic grid, an adapter with several test pins, with the adapter on a first upper side with the test pins has in electrically conductive connection contacts that a contact arrangement are adjusted on the test field, and on a second top Protruding contact tips of the test pins, each of the contact tips a specific PCB test point is assigned to a test object and at one in the Device inserted test piece with the circuit board test point of a test piece in electrically conductive contact. This device is from the above Components of the invention constructed and includes as a closed System all the advantages mentioned above.

The above object, features and advantages according to the present invention can take into account the following detailed description of the preferred embodiments of the present invention and with reference be better understood on the accompanying drawings.

Fig. 1

eine skizzierte Darstellung eines Prüfstiftes in einer ersten Ausführungsform;

Fig. 2

eine skizzierte Darstellung einer weiteren Ausführungsform eines Prüfstiftes

Fig. 3

eine skizzierte Darstellung einer weiteren Ausführungsform einer Nadel;

Fig. 4

eine skizzierte Seitenansicht einer Vorrichtung zum Prüfen mit eingesetzten Prüfling;

Fig. 5

eine Ausschnittsvergrößerung von Fig. 4 und

Fig. 6

eine Darstellung einer Prüfvorrichtung nach dem Stand der Technik.

The invention is explained in more detail below with reference to the drawings. These show in:

Fig. 1

a sketched representation of a test pin in a first embodiment;

Fig. 2

a sketched representation of a further embodiment of a test pin

Fig. 3

a sketched representation of a further embodiment of a needle;

Fig. 4

a sketched side view of a device for testing with inserted test object;

Fig. 5

an enlarged section of Fig. 4 and

Fig. 6

a representation of a test device according to the prior art.

Fig. 1 shows a test pin 1, a needle 2 and a sleeve 3 with a spring 4 comprises. The needle 2 has a total length I of approximately 40 mm to 70 mm, the sleeve one Length L from approx. 70 mm to 100 mm.

The needle 2 is with a guide area 5 in the sleeve 3 along a central axis M slidably mounted, the needle 2 with one adjoining the guide area 5 Outside area 6 protrudes freely from the sleeve 3. The outside area 6 has at one free end in a contact tip 7.

An outer diameter d1 of the needle 2 is 6 both in the outer region 0.15 to 0.30 mm and preferably also in the guide area 5 as the outer diameter d2 0.2 to 0.25 mm. The outer diameter d2 of the base region 6 is one Inner diameter D of the sleeve 3 adapted to a low-friction displaceability to ensure the needle 2 in the sleeve 3 and thereby the rigidity of the needle 2nd by guiding through the sleeve 3. This makes it possible to thin Use needles 2. This allows test pins 1 described above in one Adapters can be arranged very closely, since the outer area 6, which is in the contact tip 7 adjacent, is very thin and has a length 11 of at least 10 mm. Furthermore, the needle 2 is resiliently arranged in the test pin 1 described, so that there is an independent compensation of tolerances on a test object. In order to are the functions of the known star needles (dense arrangement) and the known Test pins (suspension) combined in the test pin.

2 shows a first exemplary embodiment of a test pin 1 according to the invention a needle 2 and a sleeve 3. The needle 2 has a base region 8 and one adjoining contact area 9. The base area 8 forms one rod-shaped section with a circular cross-section and constant diameter d2 and the contact area 9 is conically tapered towards its free end, so that it has a contact tip 7 at its free end. The diameter d of the contact tip 7 is less than or equal to 0.2 mm and is preferably 0.1 mm, thus closely spaced circuit board test points of a circuit board to be tested can be contacted. The end section opposite the contact tip 7 12 of the contact area 8 has the same diameter d2 as that Base region 8, the end section 12 also being located outside the sleeve 3 can.

Adjacent to the needle 2, the spring 4 is arranged in the sleeve 3 (Fig. 1 and Fig. 2).

In a second exemplary embodiment of the invention (FIG. 3) is an end section 14 of the base region 8 of the needle 2 is formed as a spring 4 by laser incisions 15. These laser incisions 15 can run perpendicular to the central axis M and in one plane, as shown in the illustration of FIG. 3. By a mutual The arrangement of the laser incisions 15 results overall in a meandering shape Structure of predetermined spring stiffness. To increase the travel the meander-shaped structure is adjusted in length. The spring stiffness will also by the material property and the material thickness of the between the laser incisions 15 remaining webs determined. To increase the spring properties can (indicated in the figure of Fig. 3) the laser incisions 15a be arranged at an angle <90 ° to the central axis M.

According to a further embodiment, the spring is turned by rotating the needle 2 the central axis M is manufactured with feed during the laser, so that a helical Spring 2 is made with adjustable pitch and material thickness. Besides one Laser processes are also comparable methods in the manufacture of the needle 2 and the spring 4 can be used accordingly, e.g. Etching.

The one-piece embodiments have a separate production of a spring 4 from the needle 2 and the spring 4 on several advantages. For one, can the needles 2 and others be produced in a laser process, so that in one Production step of contact area 2 is manufactured or tempered and immediately afterwards the spring 4 without the use of new tools or a changeover with set-up time can be manufactured. It is thus saving on additional materials, time and other tools a one-piece and thus easy to use arrangement made from needle 2 and spring 4. In addition, the one-piece training of needle 2 and spring 4 an ideal electrical connection between the needle 2 and the spring 4 made. Contact interfaces between needle 2 and spring 4 with their contact resistances are eliminated in the above embodiment.

The spring 4 can be used either alone or in one piece with the needle 2 are fastened together in the sleeve 3. For this purpose, the spring 4 is preferably on one end of the sleeve 3 facing away from the contact tip 7 by soldering, welding, Squeezing etc. fixed in the sleeve 3, such as shown in Fig. 1.

According to a preferred embodiment, the spring 4 is embossed, for example 16 fixed in one end region in the sleeve 3 in such a way that it prevents displacement or slipping out is secured. The fixation is preferably a Piece located away from the end of the sleeve 3, so that an end remaining Spring section remains. At this end section there is an end region 18 with a defines resilient and in particular with a spherical outer surface executed contact body 20 is formed. This contact body 20 also forms an inclination of the test pin 1 shown below due to the spring-loaded spherical outer surface always a safe electrical Contact with a contact of a basic grid (Fig. 3).

The test pins 1 in are for testing a bare printed circuit board 22 to be tested an adapter 24 (Fig. 3) arranged with which a regular basic grid a test device or a basic grid 26 on the irregular arrangement the circuit board test points 28 is implemented by the test pins 1 in the adapter 24 are partially slanted. In particular, it is possible with such an adapter 24 that many closely spaced circuit board test points 28 are tested can by adding an appropriate number of test pins 1 covering a larger area of the basic grid 26 cover, on this area of close to each other lying PCB test points 28 are directed. These test pins 1 are thus similar to a beam of rays on these closely located PCB test points 28 focused.

The test pins 1 are arranged in the adapter 24 by two spaced apart Layers 30 and a layer 31 arranged adjacent to the test specimen 22. held in which guide holes 32 are made through which the test pins 1 extend. The guide holes 32 are by drilling lasers or Etching introduced. The holes can be in relation to a level of each Layer 30, 31 have different axes from the vertical (FIG. 5).

Since the needles 2 of the test pins 1 protrude a little from the sleeve, the recesses 33 in the layer 31 adjacent to the test specimen only from the thin ones Needles 2 and not penetrated by the sleeves 3, which is why the needles 2 in the area the layer 31 can be arranged close to each other.

Basically, however, it must be taken into account that the minimum distance between the Contact tips 7 of adjacent test pins 1 cannot be reduced as desired the guide holes cannot be drilled close together as desired and in addition, drilling ridges are created during drilling, which cause a certain distance. Due to the spatial arrangement of the test pins, it is not possible to be relatively thick Provide test pins with only a small, short tip because these needles the correspondingly larger drill holes are not arranged close together can be and there is also a risk that they deal with the Touch the contact tips to adjacent areas. With the needles according to the invention these problems are caused by the large length I of the free contact area 9, which gradually tapered over a predetermined length I avoided.

These restrictions must be considered when determining the dimensions of the invention Test needle 1 can also be considered in the further. You are in an inventive However, the device is much smaller than in known devices using prior art needles. It did Basic grid field 26 of the test device has a considerable influence on the spatial arrangement the test pins 1, and since the test pins 1 are not inclined at any angle in the adapter and can be rotated, also to the minimum distance between the test probes, otherwise the test pins could touch. As in the enlargement 3 (FIG. 4) can be shown in an adapter 24 according to the invention certain reduced rigidity or flexibility of the contact tip 7 more inclined Needles 2 are used to pass the respective contact tips 7 through the adjacent ones layer 31 arranged to the test object out of its respective central axis M. to deflect reversible bending. This allows contact tips 7 even closer to each other PCB test points arranged safely and without electrically conductive Contact each other as far as possible according to the state of the art is. In particular, the contact tips 7 are essentially perpendicular to each PCB test points 28 to be contacted, so that by the described Arrangement more reliable electrical connections can be made.

It should be particularly pointed out that the production of layers 30, 31 in one Adapter 24 is a very significant cost factor in terms of manufacturing costs of an entire test fixture since the drilling pattern of each layer 30, 31 of the adapter 24 calculated separately with a computer and by CNC-controlled Precision machines with an individual hole pattern 32 must be drilled. In an adapter 24 according to the invention are described above by using inventive test pins 1 with sleeves 3 due to the increased inherent rigidity of the test pins 1 according to the invention in comparison to known needles a few layers 30.31 are required.

In particular, the adapter 24 according to the invention can be both a full grid cassette with springy pins as well as a star needle adapter to adapt one regular grid of common basic grid fields to any grid of a DUT, replace, whereby a complete component - full grid cassette on a test device or grid adjustment adapter - can be saved.

LIST OF REFERENCE NUMBERS

R

Pattern adapter

G

Basic grid

T

Circuit board test points

P

PCB to be tested

F

leadership position

N

Test pins, rigid

V

Full grid cassette

S

springy pen

1

test pin

2

needle

3

shell

4

feather

5

guide region

6

outdoors

7

contact tip

8th

base region

9

contact area
10

12

End section of the contact area 9
13

D

Inner diameter of the sleeve 3

d1

Outer diameter of the needle 2 in the outer area 6 / contact area 9

d2

Outside diameter of the needle 2 in the guide area 5 / base area 8

d

Diameter of the contact tip 7

I1

Length of the contact area

I2

Length of the base area

l

Length of the needle 2

L

Length of the sleeve 3

M

Central axis of the needle 2

14

End portion of the base portion 8 of the needle 2

15

Laser cuts

16

impressing

18

End area of the spring 4

20

(springy) contact

22

PCB / DUT

24

adapter

26

Ground grid

28

PCB checkpoint

30

Location of the adapter

31

Position of the adapter, facing the test object

32

breadboard

33

recess

Claims (16)

1. A probe for a circuit board tester comprising
   a needle (2) and
   a sleeve (3) with a sleeve inner wall,
   said needle (2) being with its outer wall in contact with the sleeve inner wall and being shiftingly guided in said sleeve (3) and
   and a spring (4) being provided in said sleeve (3) which counteracts movement of said needle (2)
   said needle (2) protruding more than 10 mm, particularly more than 20 mm, from said sleeve (3) and having a maximum diameter (d2) of 0.30 mm, and said needle (2) tapering conically to a contact tip (7) from the area projecting from the sleeve (3).
2. The probe as set forth in claim 1,
   characterized in that
   said needle (2) has a diameter d2 > 0.15 mm.
3. The probe as set forth in one or more of the previous claims,
   characterized in that
   said sleeve (3) is configured tubular and
   adapted in its inner diameter (D) to a constant outer diameter (d1, d2) of said needle (2) and
   said needle (2) is conically tapered from the transition of a base portion (8) into a contact portion (9) up to said contact tip (7).
4. The probe as set forth in one or more of the previous claims,
   characterized in that
   said contact tip has a diameter (d) of ≤ 0.2 mm and that an end portion of said contact portion (9) opposite said contact tip (7) comprises a diameter (d2) larger by at least 0.1 mm than that of said contact tip (7).
5. The probe as set forth in claim 3 or 4,
   characterized in that
   said base portion (8) has a length (I1) of at least 30 mm.
6. The probe as set forth in one or more of the previous claims,
   characterized in that
   said spring (4) is formed from an end opposite said contact tip (7) of a guide portion (5) of said needle (2) located in said sleeve (3) and is more particularly machined therefrom by laser action in the form of laser incisions (15).
7. The probe as set forth in claim 6,
   characterized in that
   said spring (4) is formed from part of said guide portion (5) of said needle (2) by laser incisions (15) standing perpendicular to the longitudinal centerline or at an angle <90° to said longitudinal centerline as a more particularly meander or spiral-shaped part.
8. The probe as set forth in one or more of the previous claims 1 to 5,
   characterized in that
   said spring (4) at the end of said guide portion (5) of said needle (2) opposite said contact tip (7) is integrally connected to said spring (4) and preferably welded in place by laser application.
9. The probe as set forth in one or more of the previous claims,
   characterized in that
   said contact portion (9) up to said contact tip (7) is defined in its stiffness or in the stiffness profile being a function of the locus.
10. The probe as set forth in one or more of the previous claims,
    characterized in that
    said needle (2) is fixed in place in said sleeve (3), preferably by crimping, folding and/or soldering.
11. An adapter comprising at least two layers (30) in parallel in which probes (1) designed as set forth in any of the previous claims are mounted in through-holes (33), said probes (1) being arranged partly canting and with protruding contact tips (7) of said probes (1) for contacting a test object (22) as well as
    said probes (1) on a side of said adapter opposite said test object (22) being configured for contacting a grid pattern array (26) with a regular arrangement of contacts.
12. The adapter as set forth in claim 11,
    characterized in that
    said contact tips (7) comprise a spacing of approx. 0.25 mm and a diameter (d) of approx. 0.1 mm.
13. The adapter as set forth in claim 11 or 12,
    characterized in that
    at least one probe (1) in said adapter (24) in the region of said contact tip (7) is deflected by at least one deflector, more particularly by a layer (31) from the longitudinal centerline (M) of said probe (1), preferably reversibly bent.
14. A circuit board tester comprising
    a regular grid pattern array (26),
    an adapter (24) including several probes (1) wherein the adapter is designed as set forth in claims 11 to 13,
    said adapter (24) comprising at a first upper side contacts (20) in electrical contact with said probes (1) which are adapted to a contact arrangement on said grid pattern array (26), and said contact tips (7) of said probes (1) protruding from a second upper side, whereby each of said contact tips (7) is assigned to a specific circuit board test point (28) of a test object (22) and is in electrical contact with said circuit board test point (28) of a test object (22) inserted in said tester.
15. The tester as set forth in claim 14,
    characterized in that
    said contact tips (7) at said second upper side of said adapter (24) comprise a spacing of ≤ 0.3 mm, preferably 0.25 mm.
16. The tester as set forth in claim 14 or 15
    characterized in that
    at least one probe (1) in said adapter (24) in the region of said contact tip (7) is deflected by at least one deflector, more particularly by a layer (31) from said longitudinal centerline (M) of said probe (1), preferably reversibly bent.

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